Abstract: The present invention is about a method for filling an opening in an insulating layer in a fast and highly reliable way and can be used to fill openings such as trenches and via holes simultaneously. This method is based on the principle of reaction enhanced wetting and simultaneous seed layer formation. The idea is, in contrast to trying to avoid the TiAl3 formation, to use this reaction to its advantage for the creation of an ultra-thin continuous Al-containing seed layer. The latter allows a bottom to top fill during the subsequent Al-containing metal deposition. As a consequence, the filling process proceeds much faster and is production worthy.